NDE Digital Methods for Predicting Stiffness and Strength of Wind Turbine Blades - Hybrid Anisotropic Materials for Wind Power Turbine Blades - page 184

TABLE 6.13
Mechanical.Properties.of.IM7/PPS.(Thermo-Lite TM. ) . Prepreg

LaminateProperty FiberOrientation TestData K -1 Ratio

Fatigue.Strength,.Ksi O 0

90 0

285
12.5

0.0117
0.083

Tensile.Modulus,.Msi O 0

90 0

24,2
1.5

Compression.Strength,.Ksi O 0 185 0.0108

2

T = Σ
Σ

ε
α

. (6.33)

.

Table 6.14.gives.the.modulus.of.elasticity.and.coeficient.of.thermal.expan-
sion.for.the.prepreg.laminates.based.on.IM7.carbon.ibers.shown.in.Table 6.12.
and.Table 6.13. 26
The.10.percent.of.Boron.ibers.volume.fraction.added.to.IM7.iber..Strain.in.
different.layers.of.the.FRP.object.correlates.with.each.layer.
We. assume.that.correlation. between.strain.Δε 2 .during. delaminating. and.
number.of.cracks.are

. Δε 2. =.(n*C) 1/2 . (6.34)

Here:
n.is.a.number.of.cracks;
C.is.a.length.of.cracks.

Value.of.parameters.are.given.in.Table 6.15.
Figure 6.7.shows.the.measured.correlation.between.temperature.gradient.
and.strain.propagation.
Reference. 28. shows. the. test. stand. used. to. measure. delaminating. cracks..
Fiber.optic.sensors.are.embedded.in.the.FRP.package.and.they.detect.laser.
light.passing.through.the.material..The.infrared.camera.measures.tempera-
ture.at.the.side.surface.boundary.of.the.package..P.is.impulse.load,.M x .is.a.
bending.moment.

TABLE 6.14
Modulus.of.Elasticity.and.Coeficient.of.Thermal.Expansion.for.the.
Prepreg.Laminates

Material IM7/PEEK IM7/PPS

Modulus.of.Elasticity,.Msi 24.2 24.2

Coeficient.of.thermal.Expansion,.PPMF -0.02 -0.06